1. Field of the Invention
This invention pertains generally to an apparatus and a method for treatment of living tissues and cells by altering their interaction with their electromagnetic environment. This invention also relates to a method of modification of cellular and tissue growth, repair, maintenance, and general behavior by application of encoded electromagnetic information. More particularly this invention relates to the application of surgically non-invasive coupling of highly specific electromagnetic signal patterns to any number of body parts. In particular, an embodiment according to the present invention pertains to using pulsing electromagnetic fields (“PEMF”) to enhance living tissue growth and repair via angiogenesis and neovascularization by affecting the precursors to growth factors and other cytokines, such as ion/ligand binding such as calcium binding to calmodoulin.
2. Discussion of Related Art
It is now well established that application of weak non-thermal electromagnetic fields (“EMF”) can result in physiologically meaningful in vivo and in vitro bioeffects.
EMF has been used in applications of bone repair and bone healing. Waveforms comprising low frequency components and low power are currently used in orthopedic clinics. Origins of using bone repair signals began by considering that an electrical pathway may constitute a means through which bone can adaptively respond to EMF signals. A linear physicochemical approach employing an electrochemical model of a cell membrane predicted a range of EMF waveform patterns for which bioeffects might be expected. Since a cell membrane was a likely EMF target, it became necessary to find a range of waveform parameters for which an induced electric field could couple electrochemically at the cellular surface, such as voltage-dependent kinetics. Extension of this linear model also involved Lorentz force analysis.
A pulsed radio frequency (“PRF”) signal derived from a 27.12 MHz continuous sine wave used for deep tissue healing is known in the prior art of diathermy. A pulsed successor of the diathermy signal was originally reported as an electromagnetic field capable of eliciting a non-thermal biological effect in the treatment of infections. PRF therapeutic applications have been reported for reduction of post-traumatic and post-operative pain and edema in soft tissues, wound healing, burn treatment and nerve regeneration. Application of EMF for the resolution of traumatic edema has become increasingly used in recent years. Results to date using PRF in animal and clinical studies suggest that edema may be measurably reduced from such electromagnetic stimulus.
Prior art considerations of EMF dosimetry have not taken into account dielectric properties of tissue structure as opposed to the properties of isolated cells.
In recent years, clinical use of non-invasive PRF at radio frequencies comprised using pulsed bursts of a 27.12 MHz sinusoidal wave, wherein each pulse burst comprises a width of sixty-five microseconds, having approximately 1,700 sinusoidal cycles per burst, and various burst repetition rates. By use of a substantially single voltage amplitude envelope with each PRF burst, one was limiting frequency components that could couple to relevant dielectric pathways in cells and tissue.
Time-varying electromagnetic fields, comprising rectangular waveforms such as pulsing electromagnetic fields, and sinusoidal waveforms such as pulsed radio frequency fields ranging from several Hertz to an about 15 to an about 40 MHz range, are clinically beneficial when used as an adjunctive therapy for a variety of musculoskeletal injuries and conditions.
Beginning in the 1960's, development of modern therapeutic and prophylactic devices was stimulated by clinical problems associated with non-union and delayed union bone fractures. Early work showed that an electrical pathway can be a means through which bone adaptively responds to mechanical input. Early therapeutic devices used implanted and semi-invasive electrodes delivering direct current (“DC”) to a fracture site. Non-invasive technologies were subsequently developed using electrical and electromagnetic fields. These modalities were originally created to provide a non-invasive “no-touch” means of inducing an electrical/mechanical waveform at a cell/tissue level. Clinical applications of these technologies in orthopaedics have led to approved applications by regulatory bodies worldwide for treatment of fractures such as non-unions and fresh fractures, as well as spine fusion. Presently several EMF devices constitute the standard armamentarium of orthopaedic clinical practice for treatment of difficult to heal fractures. The success rate for these devices has been very high. The database for this indication is large enough to enable its recommended use as a safe, non-surgical, non-invasive alternative to a first bone graft. Additional clinical indications for these technologies have been reported in double blind studies for treatment of avascular necrosis, tendinitis, osteoarthritis, wound repair, blood circulation and pain from arthritis as well as other musculoskeletal injuries.
Cellular studies have addressed effects of weak low frequency electromagnetic fields on both signal transduction pathways and growth factor synthesis. It can be shown that EMF stimulates secretion of growth factors after a short, trigger-like duration. Ion/ligand binding processes at a cell membrane are generally considered an initial EMF target pathway structure. The clinical relevance to treatments for example of bone repair, is upregulation such as modulation, of growth factor production as part of normal molecular regulation of bone repair. Cellular level studies have shown effects on calcium ion transport, cell proliferation, Insulin Growth Factor (“IGF-II”) release, and IGF-II receptor expression in osteoblasts. Effects on Insulin Growth Factor-I (“IGF-I”) and IGF-II have also been demonstrated in rat fracture callus. Stimulation of transforming growth factor beta (“TGF-β”) messenger RNA (“mRNA”) with PEMF in a bone induction model in a rat has been shown. Studies have also demonstrated upregulation of TGF-β mRNA by PEMF in human osteoblast-like cell line designated MG-63, wherein there were increases in TGF-β1, collagen, and osteocalcin synthesis. PEMF stimulated an increase in TGF-β1 in both hypertrophic and atrophic cells from human non-union tissue. Further studies demonstrated an increase in both TGF-β1 mRNA and protein in osteoblast cultures resulting from a direct effect of EMF on a calcium/calmodulin-dependent pathway. Cartilage cell studies have shown similar increases in TGF-β1 mRNA and protein synthesis from EMF, demonstrating a therapeutic application to joint repair. Various studies conclude that upregulation of growth factor production may be a common denominator in the tissue level mechanisms underlying electromagnetic stimulation. When using specific inhibitors, EMF can act through a calmodulin-dependent pathway. It has been previously reported that specific PEMF and PRF signals, as well as weak static magnetic fields, modulate Ca2+ binding to CaM in a cell-free enzyme preparation. Additionally, upregulation of mRNA for BMP2 and BMP4 with PEMF in osteoblast cultures and upregulation of TGF-β1 in bone and cartilage with PEMF have been demonstrated.
However, prior art in this field does not configure waveforms based upon a ion/ligand binding transduction pathway. Prior art waveforms are inefficient since prior art waveforms apply unnecessarily high amplitude and power to living tissues and cells, require unnecessarily long treatment time, and cannot be generated by a portable device.
Therefore, a need exists for an apparatus and a method that more effectively modulates angiogenesis and other biochemical processes that regulate tissue growth and repair, shortens treatment times, and incorporates miniaturized circuitry and light weight applicators thus allowing the apparatus to be portable and if desired disposable. A further need exists for an apparatus and method that more effectively modulates angiogenesis and other biochemical processes that regulate tissue growth and repair, shortens treatment times, and incorporates miniaturized circuitry and light weight applicators that can be constructed to be implantable.